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INTRODUCTION

REDUNDANCY

TRANSMISSIONS

STEERING

WEIGHT

MISCELLANEOUS

SUV STABILITY

DIALOG

FEEDBACK

MISCELLANEOUS

Hubcaps and Wheel Covers
Instrumentation
Tipsy and Unstable Vehicles
Fuel Capacity
Timing Belts
Throttle Linkage
Wheel Balance and Tire Truing
Control Pedals and Steering Column Geometry

You are encouraged to revisit this site periodically as items will continually be added. There is no order to this list: some items pertain to safety, others to comfort, durability, reliability and value. It is hoped that customer demands and feedback will result in factory compliance. If injury or property loss occurs as a result of your vehicle being inadequately engineered in the areas discussed below, you might consider a filing a claim against the party at fault.


HUBCAPS AND WHEEL COVERS

In the beginning there were none. Then stylists decided that hubcaps were a necessary cosmetic touch to cover the wheel hub dust cover. Most of them had the marquee of the manufacturer embossed on for some rolling advertisement. Later came along wheel covers which decorate the whole steel wheel all the way to the tire bead. I doubt engineers appreciate the extra several pounds of unsprung weight added by each wheel cover; it is desirable to keep unsprung weight as low as possible for maximum suspension system performance. But, the real danger is that there is virtually nothing to hold your wheel covers in place unless you count the spring tabs spaced all the way round the circumference. These tabs initially hold the cover in place marginally. After being removed and replaced a few times, they get bent and lose their effectiveness in grip to the inner flange of the wheel to which they are attached. This weak retention is supposed to be able to handle sometimes large inertial, vibrational and gyroscopic forces. For instance, if one applies brakes on glare ice, a wheel can experience sudden stoppage. The wheel cover can then rotate within the wheel flange and either leave the vehicle or damage or shear the valve stem, causing sudden loss of tire pressure and vehicle control. Do not try this experiment; it is suggested for factory or investigative laboratory application only: Inertial dislocation of a wheel cover can be demonstrated in a shop. Block the car wheels and raise one wheel of a driving axle off the shop floor. Drive the raised wheel with the engine or on-the-car wheel balancer motor to approximately 50 mph. Make certain that all personnel are clear, then, apply the brake pedal firmly. The spinning wheel will jerk to a stop, simulating wheel lockup on glare ice. The wheel cover will likely spin in the wheel or possibly leave the wheel with great force. Again, do not perform this experiment as it is very dangerous and possibly damaging to car suspension components. 

So, given the present state of automotive practices, occasionally a wheel cover will leave its wheel, unfortunately, when the car is in motion. If you have the occasion to drive big-city freeways, you will routinely see "lost" wheel covers.

As for my own experience, I have lost two of them over time: Once on a Los Angeles freeway, after I ran over a piece of metal in the road about the size of a 2x4 piece of lumber. Another time, on a Colorado two lane highway after I allowed my car to drift to the right and ran over the warning serrations cut into the paved roadway. The vibrations alone loosened the wheel cover. In the first case, the cover rolled harmlessly into the freeway center divider and there was no damage except for the loss to me of the wheel cover itself. In the second, the cover left the vehicle at about 60 mph and traveled ahead of the car, turned left across oncoming traffic, fortunately missed striking any vehicles and stopped harmlessly in a ditch. Had the cover caused an accident either due to a driver panicking trying to avoid it, or actually hit a vehicle, I have no doubt that I would be liable for damages.

There is a solution, manufacturers. Either get rid of these useless expensive decorations and spend the money elsewhere where it counts, or BOLT THEM ON! That's right, use three cap screws or nuts to retain them to mating fasteners welded onto the wheel at 120 degree intervals. Patented positive locking devices could be substituted if they had equal integrity to bolts. Manufacturers, continue using spring tab retention at your own risk as you have been put on notice.


INSTRUMENTATION

Early cars had excellent instrumentation, probably because engineers were in control of design projects. Of course cars don't need to emulate the instrument panel of an airplane, but the dash should have the basics: fuel level, speedometer, odometer, speedometer, tachometer, oil pressure, ammeter or voltmeter, temperature. During the low point of the 1960's and 1970's, warning lights replaced a lot of gauges. Warning lights do not give a quantitative readout; they are all-or-none devices, and by the time a warning light comes on, it is often too late. Gauges allow corrective measures to be taken, before a system fails altogether. They are especially useful by mechanics for diagnostic work; guess work leads to expensive, ineffective repairs. Gauges equate with safety. The above list of gauges should be mandatory in all cars. Optional gauges  include an array useful for diagnostic work and include: oil temperature, fuel pressure, transmission oil temperature and transmission primary oil pressure. All gauges should have color coded scales, with green normal, yellow caution, and red danger. Warning lights are good too, especially when used with audible warning signals for when the system enters the red danger zone. Manufacturers should at least offer extra gauge sets as an option on the cheaper lines and for the high-end range of models, make them standard.


TIPSY AND UNSTABLE VEHICLES

Trucks being the exception, it is mandatory without question that all passenger vehicles, especially so-called SUV's (sport utility vehicles),  be dynamically  stable under all operating conditions with respect to sliding vs. tipping. In other words, on normal crowned roads of dry concrete or macadam, and with full rated and normally distributed load, including rated roof rack load, the vehicle in question must slide, not tip, if pushed beyond its limits. Again, no matter how badly mishandled, the correctly designed vehicle will slide and not roll over unless "tripped". Some margin of safety must be built in beyond the theoretical slid vs. tip condition. Ford Motor Company has been recently hit with a multi-million dollar judgment for a Bronco II rollover accident attributed to inherent instability in cornering (it tipped instead of sliding during an evasive maneuver). The Department of Transportation has statistics that indicate  a rollover is extremely dangerous and may incur approximately a 30% fatality rate. It also usually damages the vehicle beyond economic repair. 

The two primary factors which govern the tipsiness of a car are a. height of the center of gravity and b. the track, or width between the wheels. Other conditions of stability which are important considerations are over vs. understeering , primarily governed by the longitudinal position of the center of gravity and aerodynamic stability, influenced by the shape of the car body. The layman can think of the arrow analogy: an arrow flies straight because its weight is concentrated at the front and the center of pressure is to the rear of the shaft, close to the feathers.

Front wheel drive cars are inherently more stable because propulsive forces at the front wheels reduce cornering forces at the front tires. Rear drive cars are especially unstable when the rear wheels lose traction under fast acceleration; spinning tires are incapable of  controlling side forces thus allowing "fishtailing"; also, rear propulsion causes turning moments about the center of gravity during such conditions, aggravating the problem. A very stable design is a front-wheel drive station wagon; an unstable one is a rear engine car shaped like a bug. 

It will be essential for manufacturers to resist the temptation to design tall, seemingly robust vehicles which turn out to be quite contrary to the interests of safety; engineers must have the final say on vehicles, not stylists catering to the whims of unknowing juveniles. The interested reader can delve into the mathematical details of vehicle stability in the booklet, MECHANICS OF VEHICLES, Jaroslav J. Taborek, a reprint from Machine Design, c. 1957, The Penton Publishing Co., Cleveland. For a detailed sub-web treatise on the subject of SUV  vehicles, click_here. You will be able to return to potpourri or SIXBULLETS home page. 


FUEL CAPACITY

Did the factory install a sufficiently large fuel tank? Let's assume the owner's manual states the specification as 15 gallons capacity. Your EPA fuel economy is say 25 mpg. Do some calculations: Usable fuel capacity is always one or two gallons less. In this case, close to 13 gallons. Actual mileage may be less than EPA if the car is driven over hilly or mountainous terrain, is heavily loaded, driven fast (some roads now have speed limits of 75 mph), or if bucking headwinds. Mileage in a worse case example may be closer to 20 mpg. Therefore, the range as calculated is approximately 260 miles, not 375 as might first be thought. Realistically, even 260 miles is not feasible on the open road due to the fact that there are not gasoline filling stations everywhere. Refueling stops need to be planned where there are known towns on the map. On average, gas stations might be spaced at 25 to as much as 50 miles (or more in rural western states) apart on interstate highways. Therefore, the 260 mile actual range can be diminished by 25 to 50 miles; that is, to 235 to 210 miles. This short range is certainly inconvenient and costs at least 10 mph loss on long trips because each fuel stop is time lost from high speed travel. There might be some safety compromise also, as fuel exhaustion is a real possibility if a fuel stop is missed. There is no reason why a 3000+ pound car is limited to 78 pounds of usable fuel (13 gallons x 6 lbs. per gallon). A realistic fuel capacity for a car similar to the above example is 180 pounds (30 gallons); such a car would be good for 600 miles with no reserve. A diesel car might be fitted with more capacity yet; auxiliary fuel tanks could be incorporated in fender wells to supplement the main fuel tank. Diesel fuel is less volatile and dangerous than gasoline, so total usable capacity of 40 gallons is safely feasible to yield a range of 1200 miles between fill-ups. A long cross-country drive could be made non-stop for fuel, saving much time. Of all the improvement suggestions in this web, this is one of the easiest to implement and one of the most useful.


TIMING BELTS

Sold to the public as a cheaper and quieter replacement for the timing gears and timing sprockets with silent or roller chain, then in use, the timing belt was introduced in the mid '60's.This belt, also known as the camshaft drive belt typically couples the crankshaft, distributor drive shaft, and the camshaft via sprockets keyed to each shaft. Marks are used to maintain the precise relationship, or timing, of the coupled shafts. The belt itself is a rubberized, toothed, one-piece belt with an inside layer of fabric reinforcement. It is surprisingly thin, but needs to be thin for flexibility. It is usually rated for a service life of 60,000 miles, but since this $20.00 belt can costs hundreds of dollars in labor to replace, it is often driven far longer. Its failure mode is usually skipping when it stretches and loosens, especially in very cold ambient conditions. If it skips one or two sprocket teeth, the engine usually runs, but poorly. More than that and the engine will not start, requiring the belt to be reset to proper timing; that is, if the engine is a so-called non-interference engine. In the case of of an interference engine, total engine destruction is a real possibility due to the pistons striking and bending out-of-time valves. Sometimes holes are actually punched trough piston heads. The worst failure mode is when the belt snaps. This is a particularly nasty type of breakdown: the engine will suddenly stop and in the case of an interference engine (high compression gasoline or any diesel engine) the engine cashes in. How fragile is the timing belt compared to the "old fashioned gears or chains"? Well, you can perform this experiment: with an old or spare timing belt, take an ordinary dress maker's scissors or tailor's shears used to cut paper or cloth and take a cut on this belt cross-ways. With one hand it will require only one or two squeezes on the handle to cut the belt in two. For this demonstration, cut off a short piece, about half an inch in length. Then, with cut-off piece, using your bare hands, it will be possible to bend the piece sharply and rip it in two again! You may try the same experiment with a steel timing chain, but be prepared to buy a new scissors. Some manufacturers have come to realize this problem and have eliminated timing belts in some or all models, but new cars are still being produced with these unreliable belts. Continued use of timing belts go against the engineering principle of redundancy discussed previously where it was stated that if a part cannot be duplicated, it must be made virtually unbreakable. And unbreakable a timing belt is not. Anyone who has lost an engine or for that matter been stranded and has suffered serious consequential loss due to timing belt failure, despite maintenance according to the factory schedule, should consider making a claim for damages suffered. I think an in-court demonstration  of the scissors test and presentation of a collection of the robust parts previously considered the standard of design should convince any judge or jury that the public has been taken for a ride on this inferior technology.


THROTTLE LINKAGE

There are two important issues. The first is sensitivity. As engines have been downsized, the throttle linkages have been made far too sensitive for safe, stable speed control. A slight movement at the foot pedal, possibly only 1/4 inch depression, advances the throttle progressively to enable power development sufficient for freeway speeds of 65 to 75 mph. This was all done for the sake of illusion; to give the prospective car purchaser the feeling that he has a mighty engine under the hood when in fact he doesn't. As a result, it is extremely difficult to maintain a steady speed, with speed tending to creep upward. I have labeled this type of pedal linkage as a real ticket getter! I have owned my present car ten years and have not yet mastered precise throttle modulation. I think its impossible. The most minute force differential between the throttle-closing spring and the driver's foot causes significant power level changes. Leg fatigue alone will cause this speed instability syndrome. The proper design would require 75% pedal travel to achieve 75 mph on a flat road at rated load and standard temperature and pressure. The remaining 25% travel would take it to wide-open-throttle for faster speeds, hill climbing, and overtaking. Technically, the geometry of this ideal linkage could be described as non-linear progressive control. In case you may not think such properties have been designed for cars, think again. I have driven two cars with ideal, almost identical throttles: a 1952 Chevrolet Six and a 1984 Mercedes 300 Turbo Diesel.

The second issue has to do with the occasional but deadly serious case of "stuck accelerator". Here is the likely scenario: A driver depresses the throttle pedal to pick up and when he relaxes foot pressure, the engine power fails to modulate; that is, fails to respond by reducing power. In an extreme case, there is engine runaway and the car accelerates until driver response regains control or the car crashes. This type of accident is easily explained and very simple to engineer a solution. The foot pedal is connected by metal rods or a pull cable to the carburetor or fuel injection throttle valve. When the pedal is pressed, the rods or cable open the "butterfly valve" and the resulting increase in engine volumetric efficiency causes the engine output to increase and the car accelerates. Normally, when the driver's foot pedal force is relaxed, a throttle return spring closes the throttle partially or to idle position, depending on the driver's input. But in a "stuck accelerator" situation, the throttle valve does not return, due to stickiness of the cable or linkage (possibly from lack of lubrication) or more likely from a failed throttle return spring. The only remedy the driver has in this case is to think fast and turn off the ignition switch. This is more easily said than done, because these days turning the switch one position too much will lock up the steering wheel, causing yet another emergency. Stepping on the service brake may or may not be effective; it the engine is heavily throttled, and the car is at high speed, the brakes may not be sufficient to stop the car. The engineering solution is keep the present arrangement of cable/return spring but modify the design to make it "failsafe". This is done by pivoting the accelerator pedal on a rocker shaft and adding a second cable which acts as a throttle closer. Thus a push-pull action is established. Even given a sticky linkage and or a weak or broken return spring, all the driver has to do is "rock" the pedal to manually close the throttle. This response would be quite natural and no other action need be taken to save the day


WHEEL BALANCE AND TIRE TRUING

It is undeniable that wheel vibration is detrimental to safety. Poor road handling, driver fatigue, overheating and destruction of shock absorbers (spring dampers) and wear and tear and possible failure of tires, suspension and driveline components are all proximate causes of wheels in such poor balance that they can often be seen to oscillate completely off the road surface.

I believe the public is unaware that a perfectly balanced wheel assembly, balanced off-the-car or preferably, on-the-car (to balance all the rotating mass), may not run within an acceptable level of vibration. The reason is that tires often have an out-of-round condition that unless corrected, mimic a bad balance at highway speeds. To test the theory, I suggest an inquisitive auto factory mount a wheel/tire assembly in a lathe offset 1/16 to 1/8 inch and turn the tread to produce 1/8 to 1/4 inch runout. Then balance this out-of-round wheel assembly, mount it and run the test car on a smooth road or chassis dynamometer. I guarantee your false teeth will shake loose. Then, compare it with a trued and balanced tire assembly. The benefits of tire truing will be obvious. 

Tire truing, done in the past, whereby the wheel with mounted tire, was mounted in a special lathe and the tire tread shaved until the tread runout was removed, is a rarity now. After tire truing, the wheel was balanced, usually on the car, using a Hunter Balancer. The final result was superb, with vibration-free driving up to any reasonable speed.

I do not know the reason why tire truing has fallen out of favor. Perhaps the public thinks that removing tread from a new tire is a waste of rubber and shortens its service life. Or perhaps this operation is labor and time intensive and would double the cost of tire balancing. Some road tests or consultation with tire manufacturers will determine whether or not tire life is shortened or extended by removing rubber with tire truing. My guess is that it is extended and if so, the extra cost would be offset by longer wear.

The solution will be in application of this combination procedure (truing and balancing) to the Government fleet, public education, and perhaps requiring the mandatory posting of informational notices to the public in tire shops which offer balancing services. Once the public realizes that a "computer spin balance" job is half-a-job that guarantees nothing, they might demand better service for their money.


CONTROL PEDALS AND STEERING COLUMN GEOMETRY

It is impossible to apply brake pedal force with the foot and leg in normal straight body alignment due to the fact that there is always interference between knee and steering column. The leg has to be held at about 20 degrees off-axis to the right to apply the service brake. This is extremely unsatisfactory for proper, safe modulation of brake action, especially in the case of women, older people and those who don't have enough strength in the legs. On early cars, this was not the case. Also, there is a problem with lateral and height spacing between the brake and throttle (accelerator) pedals. There needs to be enough space laterally such that if the shoe of the right foot contacts only the right edge of the brake pedal and then depressed, it cannot under any conditions, including a "low brake pedal", contact the throttle pedal. The result of simultaneous brake-throttle application can be catastrophic. One might think that if this situation occurs, the driver will know better to pull his foot from the brake (and accelerator) pedal. It will not happen; the driver will tend to press the brake harder in an attempt to stop, but in reality, continue to open-throttle the engine and subsequently cause a runaway accident. Further proof is in the history of a particular type of aircraft accident: the most experienced aircraft pilots will always crash if the aileron cables are accidentally reversed during reassembly after repairs.

There is a fix for the steering column geometry problem. If necessary, it can run almost horizontal through the dash and firewall, then be coupled to the steering gear box, through u-joints, chain and sprockets, or a gear-driven shaft. Once the steering column is rearranged, there will be plenty of knee clearance and the pedals can be spaced apart better, both side-to-side and vertically.

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